OVDAS-SERNAGEOMIN reported that during 1-28 February seismicity increased at Descabezado Grande, in the Laguna del Maule volcanic complex area. There were 127 earthquakes detected, with magnitudes 1.7 or less, mostly comprised of volcano-tectonic earthquakes. The seismic swarms were associated with deformation and considered to be at a high level. On 8 March the Alert Level was raised to Yellow.

Fumarolic activity was observed on the morning of 19 March. A white plume was rising from the summit crater during the 3 hours the observer was on Nevados de Chillán Volcano, 160 km to the S. The only recorded eruption at Descabezado Grande, in 1932, was from a crater at its NE foot. Weak fumarolic activity has been reported on the W slope at about 3,500 m, but none had previously been observed in the main crater.

Information Contacts:H. Moreno R., Univ. de Chile, Santiago.

Weekly Reports - Index

OVDAS-SERNAGEOMIN reported that during 1-28 February seismicity increased at Descabezado Grande, in the Laguna del Maule volcanic complex area. There were 127 earthquakes detected, with magnitudes 1.7 or less, mostly comprised of volcano-tectonic earthquakes. The seismic swarms were associated with deformation and considered to be at a high level. On 8 March the Alert Level was raised to Yellow.

Information is preliminary and subject to change. All times are local (unless otherwise noted)

Fumarolic activity was observed on the morning of 19 March. A white plume was rising from the summit crater during the 3 hours the observer was on Nevados de Chillán Volcano, 160 km to the S. The only recorded eruption at Descabezado Grande, in 1932, was from a crater at its NE foot. Weak fumarolic activity has been reported on the W slope at about 3,500 m, but none had previously been observed in the main crater.

Information Contacts:H. Moreno R., Univ. de Chile, Santiago.

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.

Synonyms

Descabezado del Maule

Cones

Feature Name

Feature Type

Elevation

Latitude

Longitude

Chivato, Volcán

Cone

2080 m

35° 29' 0" S

70° 51' 0" W

Manantial Pelado

Stratovolcano

2850 m

35° 30' 0" S

70° 49' 0" W

Palizada, Volcán

Stratovolcano

2640 m

35° 32' 0" S

70° 49' 0" W

Rajaderas, Volcán

Stratovolcano

3000 m

35° 32' 0" S

70° 43' 0" W

Craters

Feature Name

Feature Type

Elevation

Latitude

Longitude

Mulas, Alto de las

Fissure vent

2550 m

35° 33' 0" S

70° 48' 0" W

Domes

Feature Name

Feature Type

Elevation

Latitude

Longitude

Lengua de Vulcano
Mondaca

Dome

2048 m

35° 27' 51" S

70° 48' 1" W

Basic Data

Volcano Number

Last Known Eruption

Elevation

LatitudeLongitude

357050

1933 CE

3953 m / 12966 ft

35.58°S
70.75°W

Volcano Types

Stratovolcano(es)
Fissure vent(s)
Pyroclastic cone(s)
Lava dome

Rock Types

MajorAndesite / Basaltic Andesite
Dacite

Tectonic Setting

Subduction zoneContinental crust (> 25 km)

Population

Within 5 kmWithin 10 kmWithin 30 kmWithin 100 km

39
142
3,454
704,116

Geological Summary

Volcán Descabezado Grande is a late-Pleistocene to Holocene andesitic-to-rhyodacitic stratovolcano with a 1.4-km-wide ice-filled summit crater. Along with Cerro Azul, only 7 km to the S, Descabezado Grande lies at the center of a 20 x 30 km volcanic field. A lateral crater, which formed on the upper NNE flank in 1932 shortly after the end of the major 1932 eruption from nearby Quizapu volcano on the N flank of Cerro Azul, was the site of the only historical eruption. The Holocene Alto de las Mulas fissure on the lower NW flank produced young rhyodacitic lava flows. Numerous small late-Pleistocene to Holocene volcanic centers are located N of the volcano. The northernmost of these, Lengua de Vulcano (or Mondaca), produced a very youthful rhyodacitic lava flow that dammed the Río Lentué.

References

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography.

Eruptive History

Deformation History

There is no Deformation History data available for Descabezado Grande.

Emission History

There is no Emissions History data available for Descabezado Grande.

Photo Gallery

The summit of Descabezado Grande volcano is truncated by a 1.4-km-wide, ice-filled summit crater, giving rise to its name, which means "Large Headless Volcano." The only historical eruption of this late-Pleistocene to Holocene volcano, seen here from the west, occurred in 1932 from an upper NNE-flank vent. The 1932 crater lies out of view below and to the left of the notch at the left side of the summit crater.

Photo by Hugo Moreno (University of Chile).

Volcán Descabezado Grande, seen here from the west, is a late-Pleistocene to Holocene stratovolcano with a 1.4-km-wide ice-filled summit crater. The Holocene Alto de las Mulas fissure on the lower NW flank (out of view to the left) produced young rhyodacitic lava flows. A lateral crater formed on the upper NNE flank in 1932, shortly after the end of the major 1932 eruption from nearby Quizapú volcano. This was the site of the only historical eruption of Descabezado Grande.

Photo by Hugo Moreno (University of Chile).

Descabezado Grande (center) and Cerro Azul (middle right), seen here from the NW, are the most prominent features of a large volcanic field. The most active of the two large stratovolcanoes is 3810-m-high Cerro Azul. Quizapú, a vent that formed in 1846 on the northern flank of Cerro Azul, was the source of one of the world's largest explosive eruptions of the 20th century in April 1932. The eruption created a 600-700 m wide crater and ejected 9.5 cu km of dacitic tephra. The only historical eruption of Descabezado Grande took place later in 1932.

Photo by Jeff Post, 1988 (Smithsonian Institution).

The 2048-m-high Mondaca lava dome (bottom center) produced a large youthful rhyodacitic lava flow that traveled north and dammed the Rio Lontue, eventually reaching 7 km to the NW (upper right). This eruption may have taken place during historical time, possibly during the 19th century. The solitary small Mondaca lava dome is located NNW of the Descabezado volcano complex and west of the Calabozos caldera.

Smithsonian Sample Collections Database

Affiliated Sites

The DECADE portal, still in the developmental stage, serves as an example of the proposed interoperability between The Smithsonian Institution's Global Volcanism Program, the MAGA Database, and the EarthChem Geochemical Portal. The Deep Earth Carbon Degassing (DECADE) initiative seeks to use new and established technologies to determine accurate global fluxes of volcanic CO2 to the atmosphere, but installing CO2 monitoring networks on 20 of the world's 150 most actively degassing volcanoes. The group uses related laboratory-based studies (direct gas sampling and analysis, melt inclusions) to provide new data for direct degassing of deep earth carbon to the atmosphere.

WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.

Middle InfraRed Observation of Volcanic Activity (MIROVA) is a near real time volcanic hot-spot detection system based on the analysis of MODIS (Moderate Resolution Imaging Spectroradiometer) data. In particular, MIROVA uses the Middle InfraRed Radiation (MIR), measured over target volcanoes, in order to detect, locate and measure the heat radiation sourced from volcanic activity.

Using infrared satellite Moderate Resolution Imaging Spectroradiometer (MODIS) data, scientists at the Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, developed an automated system called MODVOLC to map thermal hot-spots in near real time. For each MODIS image, the algorithm automatically scans each 1 km pixel within it to check for high-temperature hot-spots. When one is found the date, time, location, and intensity are recorded. MODIS looks at every square km of the Earth every 48 hours, once during the day and once during the night, and the presence of two MODIS sensors in space allows at least four hot-spot observations every two days. Each day updated global maps are compiled to display the locations of all hot spots detected in the previous 24 hours. There is a drop-down list with volcano names which allow users to 'zoom-in' and examine the distribution of hot-spots at a variety of spatial scales.

EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).